Integrated circuits (ICs) are designed to operate under a variety of environmental conditions. For example, ICs are designed to operate over a range of temperatures. To ensure that an IC operates correctly over a particular range of temperatures, the IC is coupled to a test unit for testing at different temperatures within the particular range. The test unit typically includes a thermal unit that facilitates thermal heating/cooling and control for testing.
Current thermal systems that control device temperature during testing implement a traditional approach by attempting to control to a fixed temperature setpoint. However, modern complex IC devices have diverse thermal management requirements during testing. Such requirements include an accurate, stable, fixed temperature with near isothermal conditions calibrating the device's built in temperature sensors, a rapidly responding temperature control to minimize device temperature changes while device power is changing dynamically during a test, and different target test temperatures depending on the product's inherent performance and targeted application. The change in target temperature is on a device by device basis and actually changes as the device test flow is progressing.
Additionally, there may be a need to change test temperature on an IC while the device is in a test socket in order to accommodate new test applications. For example, during hot testing, test data may indicate the need for the device to also be tested at a cold test temperature to adequately screen for possible defect types. A device test socket may include stress screening at temperatures that are elevated relative to the testing temperature.